Such a straight plug-in connector for hollow sections of spacer frames in insulating glass panes has become known from DE 20 2004 004 734. It is designed as having two parts, whereby the U-shaped connector parts can be plugged into one another in a positive-locking manner and can be fixed. The outer connector part has, in the area of the connection point, a center stop, which consists of four laterally deflected spring bosses, which make a spring motion transversely to the wall plane. The elastic stop elements are arranged at each side wall in pairs and on both sides of the connection point. They are located at the free edge of the side walls, which have a reduced height in this area. The inner connector part has a depression in the middle area and constrictions on both sides, as a result of which clearances are created for receiving a sealant. Due to the depressed side walls of the outer connector part, the sealant can come into contact with the inner wall of the pushed-on spacer hollow sections. Their supportive cross section is reduced by the depression of the outer side walls.
DE 94 11 067 U1 shows a one-part, U-shaped plug-in connector, in which the middle stop consists of two bending-resistant stop dogs acting on one side and directed opposite one another. Each of the side walls carries one of these rigid stop dogs at its edge, which are arranged on both sides of the connection point. The stop dogs have a wedge shape with a guide slope and a steeply rebounding stop edge. During pushing on, the hollow sections slide on the guide slope of one stop dog and abut against the stop edge of the other stop dog. Due to the sliding onto the rigid guide slope, the hollow sections are raised on one side and rotate somewhat about their longitudinal axis. Moreover, this motion brings about a sufficient height clearance of the plug-in connector in the hollow sections.